I favor withdrawal of the REMF-MULTIPLE issue.
Here's why: The only thing that CLtL pages 163-167 says about
duplicated indicators on plists is that there aren't any
(first line on page 164). Contrary to what I thought, it does
not even guarantee that GETF returns the first occurrence.
If we're going to extend Common Lisp to allow duplicated indicators on
plists, we should do it for all the property list functions, not
just REMF and REMPROP.